py3: add missing b'' literal to sshprotoext.py
Everywhere else in this file uses b''. I must have missed a line
when I wrote this code a few days ago.
# skip-blame b prefix
Differential Revision: https://phab.mercurial-scm.org/D2173
# name space package to host third party extensions
from __future__ import absolute_import
import pkgutil
__path__ = pkgutil.extend_path(__path__, __name__)